Addison, on Blood-corpuscles, 
21 
to float out in the two fluids, we find them experiencing further, 
but different, changes of form. In the alkaline fluid the phases 
A, B, fig. 2, and in the acid fluid the phases c, d, e, fig. 3, 
will be seen. Again, take a small drop of blood and place 
close to it an equal quantity of the alkaline-saline liquid, 
drop down upon them a thin piece of glass, and when a mul- 
titude of the corpuscles have floated out into the fluid and 
have assumed forms fig. 2, add at an edge of the covering- 
glass a drop of the diluted hydrochloric acid, and these forms 
will be seen changing into the forms fig. 3. Lastly, take a 
drop of blood and place near to it an equal amount of the 
acid-sugar solution, let fall upon them a thin covering-glass, 
and after a little time numerous corpuscles will be found of 
the forms represented fig. 3, add at an edge of the covering- 
glass a drop of liquor potassm, and forms fig. 3 will alter into 
forms fig. 2. The changes described may take place quickly 
or more slowly, according as the added fluid flows with more 
or less rapidity ; in the latter case it will be remarked that 
the corpuscles in progress of change from one form to the 
other regain for a brief space of time their normal figure and 
appearance (fig. 1) . We are able, then, by an appropriate appli- 
cation of alkaline and acid fluids to impress particular forms 
upon the red corpuscles of human blood, and we see them 
during the transition from one form to another regain their 
normal characters and aspect. 
This property of change of form in the corpuscles of the 
blood is not of long duration, it remains with them but for a 
limited period after their withdrawal from the circulation, 
and some of the corpuscles appear to lose it sooner than 
others, for, after a little time, corpuscles of different forms 
are to be seen floating side by side in the same current, 
and the further addition of an alkaline or acid fluid destroys 
them, without inducing any further change of figure. 
We have called forms fig. 2 alkaline, and forms fig. 3 
acid forms, not because they are exclusively determined in 
the one case by alkaline and in the other by acid liquids, 
but because the alkali potash will change the normal form 
fig. 1, and also forms fig. 3, into the forms fig. 2, and, again, 
because the hydrochloric and other acids will alter the nor- 
mal form, and also the forms fig. 2, into forms fig. 3, when 
they are properly applied. 
In repeating these experiments, it will be seen that cor- 
puscles which approach near to an edge of the covering- glass, 
whatever may be their form, lose thereby all power of fur- 
ther change. 
Now forms b, fig. 2, which result from contact with alka- 
